ML 432 not enough?

I am using a ML 432 to power up my Magnepans 3.6R. Since the beggining it felt I was not getting enough oomph. Could this be possible? This thing is 2X400 wpc at 8ohms. What am I to do? Next thing is the 33 or 33h which is seriously more expensive (esp. for those of us in Europe). Any feedback welcome.